Switchable assembly bearing with hydraulic damping

ABSTRACT

The invention relates to a switchable assembly bearing that comprises at least one working chamber and one compensation chamber which are separated by a dividing wall. The working chamber and compensation chamber are hydraulically interconnected by means of a damping channel, in addition to at least one other damping channel which can be closed by means of the sealed arrangement of a shut-off body which can be displaced along a displacement path. The other damping channel is formed and arranged in relation to the axis of symmetry of the bearing in such a way that the forces acting on the shut-off body by means of the hydraulic fluid counterbalance each other.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No.PCT/EP03/03124, filed Mar. 26, 2003. This application claims the benefitof German Patent Application 102 13 996.2, filed Mar. 27, 2002. Thedisclosures of the above applications are incorporated herein byreference.

FIELD OF THE INVENTION

The invention relates to a switchable assembly bearing with hydraulicdamping, particularly for supporting drive assemblies and/or gearboxassemblies in motor vehicles. The bearing comprises at least one workingchamber and one compensation chamber that are separated from one anotherby a dividing wall. The working chamber and compensation chamber areinterconnected hydraulically by means of a damping channel, and at leastone additional damping channel that can be closed by means of a shut-offbody displaceable along a displacement path. The shut-off body iscapable of providing a seal in cooperation with an associated seat.

DESCRIPTION OF THE PRIOR ART

An assembly bearing is known from, for example, DE 198 61 063 C2. Theknown assembly bearing has a working space and a compensation space witha dividing wall disposed between them. Moreover, between the workingspace and the compensation space the known assembly bearing comprises adamping channel for damping low-frequency, high-amplitude vibrations.For isolating high-frequency, low-amplitude vibrations there is provideda membrane disposed in a recess and capable of moving back and forth inthe direction of the vibrations introduced. In addition, the knownassembly bearing is provided centrally within the dividing wall with anaperture that can be closed in a sealing manner by means of a shut-offbody that is displaceable within the bearing and cooperates with anassociated seat in the dividing wall.

In an axial direction, the dividing wall consists of two parts and formsa membrane cage. The membrane is disposed within the membrane cage. Themembrane is made of an elastomeric material, is circular in shape andhas a central recess corresponding to the aperture.

For quenching of vibrations caused during the idling of an attachedinternal combustion engine, the sealing body is removed from theaperture by downward axial displacement so that the liquid column canmove within the aperture out of phase relative to the vibrations causedby the idling. This produces a quenching effect.

During the operation of the internal combustion engine above the idlingrotational speed, the aperture is closed by the sealing body, and underthese operating conditions the bearing of the invention functions as dothe generally known hydraulically damping bearings, in which, to isolatehigh-frequency, low-amplitude engine-induced vibrations, the membrane isdisposed within the dividing wall so that it can move back and forth.For the damping of low-frequency, high-amplitude, roadway-inducedvibrations, the damping liquid contained within the damping channelvibrates back and forth in an out-of-phase manner.

A drawback of the known assembly bearing, however, is that the centralaperture strongly reduces the surface area available for the membrane.This has a deleterious effect on the damping of low-amplitude,high-frequency acoustic vibrations. Moreover, in the central aperturethe sealing body must be able to resist or move against the increasedpressure in the working space, which requires higher displacementforces. Other drawbacks are the complicated design of the known assemblybearing and the large dimensions thereof.

SUMMARY OF THE INVENTION

An object of the present invention is to further develop an assemblybearing in a manner such that it will be of simpler design and require asmaller mounting space and, in addition, reduced displacement forces foridling.

The present invention makes use in simple manner of the symmetry of anassembly bearing relative to its long axis. According to the invention,a switchable assembly bearing with hydraulic damping, particularly forthe support of drive assemblies and/or gearbox assemblies in motorvehicles, is provided that comprises at least one working chamber andone compensation chamber that are separated by a dividing wall. Theworking chamber and compensation chamber are hydraulicallyinterconnected through a damping channel, and at least one additionaldamping channel that can be closed by a shut-off body displaceable alonga displacement path and cooperating with an associated seat. Theadditional damping channel is configured and disposed relative to thesymmetry axis of the bearing so that the forces acting on the shut-offbody through the hydraulic liquid counterbalance each other. This hasthe advantage that substantially lower displacement forces are needed todisplace the shut-off body and, as a result, the assembly bearing can beof small and compact design.

In an advantageous embodiment of the invention, the damping channel isformed in a simple manner as an annular slot that extends radiallyaround the aperture between the working chamber and the compensationchamber, with a passage opening disposed radially relative to thesymmetry axis toward a corresponding annular slot-like connectingchamber that leads to the compensation chamber. In this embodiment, theshut-off body is formed by a sealing ring displaceable back and forthalong a displacement path that extends vertical to the flow-throughdirection, namely parallel to the bearing axis, between an openingposition and a closing position. With such a technical arrangement, bymaking use of the symmetry of the assembly bearing, it is possible toachieve virtual compensation of the forces acting on the shut-off body.Such forces are a result of a pressure build-up in the working chamber.These forces act generally on the sealing ring in the direction verticalto the displacement path and counterbalance each other. On the side ofthe compensation chamber, a pressure build-up that could producetroublesome forces is largely prevented by the connection with thecompensation chamber which at the bottom is limited by air bellowscapable of absorbing volume without generating pressure.

In addition to the fact that the damping channel is designed as anannular slot and the shut-off body as a sealing ring, it is alsopossible to make use of several passage openings disposed diametricallyopposite each other and whose shut-off bodies are operationallyconnected with each other. In such an arrangement, too, by making use ofthe symmetry, nearly complete force compensation can be achieved.

In a particularly preferred embodiment of the invention, the chamberproviding the connection to the compensation chamber is attached to theadditional damping channel in a radially outward direction. This has theadvantage that the entire inner surface of the dividing wall isavailable for the placement of the membrane.

Because, as a result of extensive force compensation, only slightdisplacement forces are needed, magnetic forces can be used to actuatethe shut-off body or the sealing ring. To this end, the shut-off body orthe sealing ring are advantageously provided with a permanently magneticmaterial, and a device is provided for generating the appropriateswitching magnetic fields.

The device for generating magnetic fields is preferably anelectromagnet.

When the additional damping channel is in the form of an annular slotand the shut-off body in the form of a sealing ring, the electromagnetis advantageously, at least in segments, in the form of a ringcorresponding to the sealing ring.

In an especially simple space-saving design, the electromagnet isdisposed in a chamber adjacent to the chamber connecting with thecompensation space containing the shut-off body.

In another particularly preferred embodiment of the invention, theshut-off body or the sealing ring consists of a magnetic elastomer. Thedensity of elastomers is preferably in the range of the density of thedamping liquid so that as a result of this measure the displacementforces for the shut-off body are further reduced.

The required mounting space is further minimized when the dampingchannel is at least partly disposed in the dividing wall between theworking chamber and the compensation chamber.

In particular, the additional damping channel is sized so that it issuitable for decoupling and quenching low-frequency, high-amplitudevibrations of an idling drive assembly.

If, besides the first and the additional damping channel, the switchableassembly bearing of the invention is provided with yet another knowndecoupling device for quenching and damping high-frequency,low-amplitude acoustic vibrations, the switchable assembly bearing ofthe invention combines in itself all advantages of an idling switchablebearing in itself known, but in contrast to the known versions ischaracterized by a simple design, compact construction and low energyrequirements.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be explained in greater detail byreference to the drawings in which:

FIGS. 1 a and 1 b show a schematic representation of a longitudinalsection of a preferred embodiment of a switchable assembly bearing inthe closed position (a) and with the additional damping channel open(b).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

FIGS. 1 a and 1 b show a hydraulically damped assembly bearing 1provided with a working chamber 10 and a compensation chamber 20 whichare filled with a common hydraulic fluid. Working chamber 10 is limitedby a wall 3 having a truncated conical shape and made of an elasticmaterial, known as the bearing spring. Compensation chamber 20 islimited at the bottom by a cup-shaped wall 4, also made of an elasticmaterial, for example by an air bellows capable of absorbing volumewithout creating pressure. On the side of the engine, a peripheral wall3 receives a bearing plate 3.1. The plate is provided with a protrudingscrew bolt 3.2 for fastening to the engine. Between working chamber 10and compensation chamber 20 is located a dividing wall 50 in which isdisposed a membrane cage 52 for receiving a membrane 54. In the dividingwall 50 is also disposed a damping channel 60 which hydraulicallyinterconnects the two liquid-filled chambers 10 and 20. The lowerlimiting wall 4 of compensation chamber 20 is surrounded by a housing4.1 on which there is provided a vertically protruding screw bolt 4.2for fastening assembly bearing 1 on the side of the vehicle body.

According to the invention, an additional damping channel 70 forquenching the idling-induced vibrations is disposed in dividing wall 50.It can be seen in the sectional representation of the present embodimentthat the additional damping channel 70 makes an approximately 90° bendfrom the vertical to the horizontal direction and ends in connectingchamber 80 which provides the connection with compensation chamber 20.This means that in the embodiment shown, the additional damping channel70 and the connecting chamber 80 constitute an annular slot in the formof a peripherally extending aperture. In connecting chamber 80 islocated as a shut-off body a sealing ring 90 made of an elastomericmagnetic material. In connecting chamber 80, the sealing ring 90 ismovable back and forth in the axial direction between an open positionand a closed position between two studs 81, 82 that act as stops.

It can be seen from FIGS. 1 a and 1 b that the displacement path ofsealing ring 90 extends vertically in the direction of the mouth ofadditional damping channel 70. It is made certain in this manner thatsealing ring 90, even if subjected to a pressure stress, can continue tomove through additional channel 70 virtually without force application,because the forces acting on the sealing ring from the side of theworking chamber counterbalance each other. On the side of thecompensation chamber, the build-up of a pressure gradient that couldlead to troublesome forces is prevented by an air bellows 4 that iscapable of absorbing volume without creating pressure. To actuatesealing ring 90 there is provided an electromagnet 100 which incorrespondence with sealing ring 90 also extends peripherally and whichis disposed in a chamber 85 that is directly adjacent to connectingchamber 80. In the closed position shown in FIG. 1, sealing ring 90rests on the lower stud 82 and with its internal radial surface sealsthe additional damping channel 70 in liquid-tight manner.

The polarity reversal of the electromagnet puts sealing ring 90 into theopen position represented in FIG. 1 b. The ring 90 touches upper stud 81thus freeing the passage opening of the additional damping channel 70toward connecting chamber 80.

Because of its permanent magnetic properties, sealing ring 90 can bekept in the position shown without the need for a current.

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A switchable assembly bearing with hydraulic damping, particularlyfor supporting drive assemblies and/or gearbox assemblies in motorvehicles, comprising: at least one working chamber and one compensationchamber that are separated from one another by a dividing wall, saidworking chamber and said compensation chamber being hydraulicallyinterconnected through a damping channel and at least one additionaldamping channel that are formed in said dividing wall, said additionaldamping channel being arcuately formed in said dividing wall andhydraulically interconnecting said working chamber and said compensationchamber through a connecting chamber, said connecting chamber housing ashut-off body separate and apart from said dividing wall that isdisplaceable from a first position that enables fluid communicationthrough said connecting chamber and a second position that closes saidadditional damping channel to disable fluid communication through saidconnecting chamber, wherein said additional damping channel isconfigured and disposed relative to a symmetry axis of the bearing sothat forces acting on said shut-off body through a hydraulic liquidcounterbalance each other.
 2. The switchable assembly bearing accordingto claim 1, wherein said additional damping channel and said connectingchamber form a radially surrounding annular slot with a passage openingdisposed radially relative to said symmetry axis and directed towardsaid compensation chamber; and said shut-off body is formed by a sealingring disposed at said passage opening and is displaceable along adisplacement path that extends vertical to said passage opening betweensaid first position and said second position.
 3. The switchable assemblybearing according to claim 2, wherein said passage opening pointsradially outward.
 4. The switchable assembly bearing according to claim1, wherein said shut-off body comprises a permanently magnetic materialand the bearing further comprises a device for actuating said shut-offbody by magnetic forces.
 5. The switchable assembly bearing according toclaim 4, wherein the device for actuating the shut-off body is anelectromagnet.
 6. The switchable assembly bearing according to claim 5,wherein at least segments of the electromagnet are also ring-shaped. 7.The switchable assembly bearing according to claim 5, wherein theelectromagnet is disposed in a chamber adjacent to the connectingchamber containing the shut-off body and which provides a connectionwith the compensation chamber.
 8. The switchable assembly bearingaccording to claim 4, wherein the shut-off body is made of a magneticelastomer.
 9. The switchable assembly bearing according to claim 1,wherein the additional damping channel for decoupling and quenchinglow-frequency, high-amplitude vibrations is designed for an idling driveassembly.
 10. The switchable assembly bearing according to claim 1,further comprising a decoupling device for quenching and dampinghigh-frequency, low-amplitude acoustic vibrations.
 11. A bearingassembly comprising: a working chamber; a compensation chamber in fluidcommunication with said working chamber through a first damping channel;and a connecting chamber fluidly connecting said working chamber andsaid compensation chamber through an arcuately formed second dampingchannel; wherein said first and second damping channels are formed in adividing wall that separates said working chamber and said compensationchamber; said connecting chamber includes a sealing ring separate andapart from said dividing wall that is movable between an open positionand a closed position such that said sealing ring can open and closesaid second damping channel of said dividing wall.
 12. The bearingassembly according to claim 11, further comprising an electromagnetdisposed in said connecting chamber.
 13. The bearing assembly accordingto claim 12, wherein said electromagnet moves said sealing ring betweensaid open and said closed position.
 14. The bearing assembly accordingto claim 11, wherein said sealing ring is comprised of a magneticelastomer.